Another view of the cloud. (Photo: Stephanie Nohrden via the Sun Sentinel)

But there's a more likely theory, according to scientists, as to what the mysterious cloud is:

Meteorologists in Melbourne said the sight was nothing to be alarmed about. "There is no reason to be freaking out," laughed National Weather Service meteorologist John Pendergrast, based in Brevard County.

Scientists believe the swirly white or electric-bluish cloud was caused by the exhaust plume of the rocket, which formed a cloud of ice crystals 240,000 to 280,000 feet above Earth. The illumination was caused by the sun still shining at that height.

A United Launch Alliance Delta IV rocket lifts off from Cape Canaveral Air Force Station, Fla Wednesday, Aug. 7, 2013. The rocket is carrying a Wideband Global SATCOM (WGS-6) satellite for the U.S. Air Force. (Photo: AP/Florida Today, Craig Bailey)

Watch this footage of the cloud sent to the Sun Sentinel from its reader Meredith Hockaday:

What some had considered spacecraft, the Sun Sentinel reported scientists saying, were likely the rocket booster and rocket separating.

"The craziest thing by far had to be when two circular light objects descended from under the light blue vortex side by side in a symmetrical manner, hovering at the same speed, until one of the UFOs flew on ahead picking up speed," Terrell Quamina wrote of what she saw in an email, according to the Sun Sentinel. "The second UFO then came to a full stop and just basically floated in one spot."

A ULA Delta IV rocket blasts off from Launch Complex 37 at Cape Canaveral Air Force Station carrying a military satellite, seen over the top of Cruise Terminal 6, Wednesday, Aug. 7, 2013 at Port Canaveral, Fla. (Photo: AP/Malcom Denemark)

The newspaper confirmed with the U.S. Air Force that it had launched a satellite, which will be used to improve military communication, that night.